QotD: What's Your Favorite Joke?

Since we’re still dealing with the last joke’s aftermath, I thought this would be a good question of the day:

What’s your favorite joke?

Warning: If you’re a sensitive person, stay out of the comments — unless you like being offended (but if so, you don’t need to tell us).

Forward Thinking: Civic Responsibility
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QotD: Free Speech?
Questions of the Day: Design.